Trading in CBOE index options was up 28 percent in the quarter from a year earlier to 1.5 million on an average day, even as trading in options on individual stocks, which are offered at CBOE's 10 rival exchanges as well, sank.

CBOE's S&P 500 and VIX options are licensed and not offered at any other exchanges, allowing CBOE is able to command much higher fees for them. But trading in them was interrupted twice in the last few days because of a software bug, preventing investors from accessing the contracts, raising questions about the Chicago exchange's hold on the contracts.

Chief Executive William Brodsky and CEO-designate Ed Tilly have vigorously defended CBOE's right to list the products exclusively, and that strategy has been the centerpiece of the company's strategy. Rivals have unsuccessfully challenged that right in court for years.

The contracts are used by institutional as well as retail investors to bet on and hedge against swings in the overall U.S. stock markets.

Including both CBOE's options and futures exchanges, index-based contracts accounted for 37.9 percent of total trades, compared with 25.4 percent a year earlier, the company said.

That drove a jump in the fee CBOE collected, on average, from each trade in the quarter to 37.8 cents from 28 cents in the prior year's period.